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you have an HCI solution with a olarity of 0.0045M. What is the [H+]?

2 years ago

Answered By Mat B

This question is dealing with HCl (aq), which is characterized as a strong acid aqeuous solution.  When asked about molarity of a strong acid in a solution, remember that a strong acid will completely ionize in water.  Let's look at the equation.

HCl (aq)-->H+(aq)+Cl-(aq) Its important to notice here that the equation balances out so that all compounds, both reactants and products, are at a 1:1 mole ratio.  Here is another way to think about it


This means that you will have the same number of moles, or the same number of molecules for all compounds in the reaction.  So if the concentration of HCl in the solution is 0.0045M, there will also be a concentration of 0.0045M of H+ ions in the products.  The concentration of H+ ions on the product side doesn't change from the concentration of the HCl reactants because strong acids react completely in the solution, and the amount of moles is also a 1:1 rate for all compounds involved.  Fortunately no other calculations are needed.

Answer: [H+]=0.0045M

2 years ago

Answered By Kaushik S

HCl is considered a strong acid, which means that it will dissociate in water (otherwise termed as aqueous state or solution) into its constituent icons of H+ and Cl- (both aqueous). 

Before calculating the concentration of the lions, it is important to ensure that the equation us balanced. Since the oxidation state of both H and Cl is 1, the coefficients of HCl, H+ and Cl- are 1 to get a balanced dissociation equation.

This means that 1 mole of HCl gives rise to 1 mole of each of the constituent ions. Since molarity is mol/L, the volume is the common basis. So 0.0045 moles of HCl will give rise to 0.0045 moles of H+. Thus, the concentration of [H+] is 0.0045 mol/L.